Russian state arms producer Almaz-Antei said on June 2 that it would supply Iran with the advanced S-300 missile-defense system once a commercial agreement is reached.
It said the Russian authorities had removed all restrictions on deliveries.
Moscow scrapped a deal to sell S-300 systems to Iran in 2010 under pressure from the West but President Vladimir Putin signed a decree in April ending the self-imposed ban.
The Russian move has been strongly criticized by the United States and Israel.
On May 25, Iranian Deputy Foreign Minister Hossein Amir-Abdollahian said delivery of the S-300 missile systems should take place soon.